Chemical Effects of Electric Current Part 4: MCQs (Q76–Q100)
⚡ Chemical Effects of Electric Current – MCQs for Class 8 Science
Part 4: Q76–Q100
Q76. Which one is NOT an application of electroplating?
A) Making jewelry attractive
B) Protecting car parts
C) Cooking food
D) Preventing corrosion
✅ Correct Answer: C) Cooking food
Explanation:
- C) ✔ Electroplating is never used for cooking.
- A, B, D are real applications.
Q77. In electrolysis of acidified water, the gas collected at cathode is:
A) Oxygen
B) Hydrogen
C) Carbon dioxide
D) Nitrogen
✅ Correct Answer: B) Hydrogen
Explanation:
- B) ✔ H⁺ ions reduce to H₂ at cathode.
Q78. In electroplating, the object to be electroplated is connected to:
A) Anode
B) Cathode
C) Both
D) None
✅ Correct Answer: B) Cathode
Explanation:
- B) ✔ Metal ions deposit on cathode = object to be coated.
Q79. The positive electrode in an electrolytic cell is called:
A) Cathode
B) Anode
C) Grid
D) Plate
✅ Correct Answer: B) Anode
Explanation:
- B) ✔ Anode = positive terminal where oxidation occurs.
Q80. The liquid that conducts electricity due to ions is called:
A) Electrolyte
B) Conductor
C) Insulator
D) Magnet
✅ Correct Answer: A) Electrolyte
Explanation:
- A) ✔ Solutions of salts, acids, and bases are electrolytes.
Q81. Which one among these is NOT used as electrolyte?
A) Copper sulphate solution
B) Silver nitrate solution
C) Sugar solution
D) Nickel sulphate solution
✅ Correct Answer: C) Sugar solution
Explanation:
- C) ✔ Sugar does not ionize → non-conductor.
Q82. Why is DC used in electroplating instead of AC?
A) DC is safer
B) DC gives steady ion movement
C) AC deposits uneven layers
D) Both B and C
✅ Correct Answer: D) Both B and C
Explanation:
- D) ✔ DC ensures uniform deposition → AC reverses direction, disturbing plating.
Q83. During electroplating, the thickness of the coating depends on:
A) Current strength
B) Time of current flow
C) Electrolyte concentration
D) All of these
✅ Correct Answer: D) All of these
Explanation:
- D) ✔ All influence deposition quality and thickness.
Q84. In which industry is electroplating most commonly used?
A) Textile industry
B) Automotive industry
C) Paper industry
D) Cement industry
✅ Correct Answer: B) Automotive industry
Explanation:
- B) ✔ Car parts and machinery are chromium/nickel plated.
Q85. Electrolysis of copper sulphate solution using platinum electrodes gives:
A) Hydrogen and oxygen
B) Copper and sulphur
C) Copper and oxygen
D) Hydrogen and chlorine
✅ Correct Answer: C) Copper and oxygen
Explanation:
- C) ✔ Cu²⁺ → copper at cathode, O₂ at anode.
Q86. Which one is a disadvantage of electroplating?
A) Requires electricity
B) Takes time
C) Produces harmful by-products
D) All of these
✅ Correct Answer: D) All of these
Explanation:
- D) ✔ Electroplating needs power, is slow, and may release toxic chemicals.
Q87. The electrode where reduction occurs is called:
A) Anode
B) Cathode
C) Both
D) None
✅ Correct Answer: B) Cathode
Explanation:
- B) ✔ Reduction always occurs at cathode.
Q88. Which metal is used to electroplate tin cans?
A) Tin
B) Zinc
C) Lead
D) Nickel
✅ Correct Answer: A) Tin
Explanation:
- A) ✔ Food cans are tin-plated to avoid rusting.
Q89. During electrolysis, which particles actually carry charge through the solution?
A) Protons
B) Ions
C) Electrons
D) Neutrons
✅ Correct Answer: B) Ions
Explanation:
- B) ✔ Cations & anions move, conducting current in electrolyte.
Q90. The term “electroplating” means:
A) Coating of metal by paint
B) Coating of metal by another metal using electricity
C) Coating of plastic by electricity
D) None
✅ Correct Answer: B) Coating of metal by another metal using electricity
Explanation:
- B) ✔ Electroplating = thin metallic layer deposition.
Q91. The effect of electric current used in electrolysis is:
A) Heating effect
B) Chemical effect
C) Magnetic effect
D) Light effect
✅ Correct Answer: B) Chemical effect
Explanation:
- B) ✔ Electrolysis is due to chemical effect of current.
Q92. What is released at the cathode during electrolysis of acidified water?
A) Hydrogen
B) Oxygen
C) Chlorine
D) Nitrogen
✅ Correct Answer: A) Hydrogen
Explanation:
- A) ✔ H⁺ ions gain electrons → H₂ gas.
Q93. Which gas is collected at the anode during electrolysis of water?
A) Hydrogen
B) Oxygen
C) Chlorine
D) Carbon dioxide
✅ Correct Answer: B) Oxygen
Explanation:
- B) ✔ OH⁻ ions oxidize → O₂ gas.
Q94. The colour of copper sulphate solution fades during electrolysis because:
A) Copper deposits at cathode
B) Copper dissolves at anode
C) Both A and B
D) None
✅ Correct Answer: C) Both A and B
Explanation:
- C) ✔ Copper ions keep moving → solution colour decreases.
Q95. Which property of metals is improved by electroplating?
A) Ductility
B) Strength
C) Corrosion resistance
D) Melting point
✅ Correct Answer: C) Corrosion resistance
Explanation:
- C) ✔ Electroplating prevents rust and increases durability.
Q96. Which solution is used for silver plating?
A) Copper sulphate
B) Silver nitrate
C) Zinc sulphate
D) Sodium hydroxide
✅ Correct Answer: B) Silver nitrate
Explanation:
- B) ✔ Provides Ag⁺ ions → silver coating on objects.
Q97. Which gas is released at the cathode during electrolysis of brine?
A) Hydrogen
B) Oxygen
C) Chlorine
D) Carbon dioxide
✅ Correct Answer: A) Hydrogen
Explanation:
- A) ✔ H⁺ ions reduce to hydrogen gas.
Q98. The electrolyte used in gold plating is:
A) Silver nitrate
B) Gold chloride
C) Nickel sulphate
D) Copper sulphate
✅ Correct Answer: B) Gold chloride
Explanation:
- B) ✔ Provides Au³⁺ ions → gold deposited on surface.
Q99. Electrorefining of metals is used for:
A) Making alloys
B) Purification of metals
C) Increasing hardness
D) Reducing weight
✅ Correct Answer: B) Purification of metals
Explanation:
- B) ✔ Impure metal as anode, pure metal deposited at cathode.
Q100. Which one of these proves chemical effect of current?
A) Bulb glowing
B) Magnetization
C) Copper deposition on iron
D) Heating of wire
✅ Correct Answer: C) Copper deposition on iron
Explanation:
- C) ✔ Deposition of copper shows chemical effect of current.
Chemical Effects Class 8 MCQs, CBSE Class 8 Science MCQs, NCERT Class 8 Chemical Effects Questions, Online Learning Science MCQs, Important MCQs Class 8, cbse class 8 science chemical effects mcqs with answers, ncert class 8 chemical effects of electric current objective questions, important mcqs for class 8 chemical effects board exams, online learning mcqs for class 8 science chemical effects, chapter wise mcqs for class 8 science chemical effects